1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor substrate provided with a single crystal semiconductor layer over a supporting substrate by a bonding method, that is, a method for manufacturing an SOI substrate by an attaching method. More specifically, the present invention relates to a method for manufacturing a semiconductor substrate in which a single crystal semiconductor layer is bonded to a supporting substrate briefly and efficiently by an attaching method.
2. Description of the Related Art
A technique relating to a semiconductor substrate in which a single crystal silicon layer is provided over an insulating supporting substrate such as a heat-resistant glass, that is, an SOI substrate, has been known (see Reference 1: Japanese Published Patent Application No. H11-163363). The semiconductor substrate is manufactured by a method in which the entire surface of crystallized glass having a strain point of greater than or equal to 750° C. is protected with an insulating silicon film, and the single crystal silicon layer obtained by a hydrogen ion implantation separation method is bonded to the insulating silicon film. The hydrogen ion implantation separation method includes a step of disposing surfaces of a supporting substrate and a wafer single crystal silicon layer in close contact with each other to be subjected to heat treatment and transferring the single crystal silicon layer, that is, a step of attaching.
If any surface has a foreign substance (dust) in the step of attaching, the single crystal silicon layer is not transferred to the supporting substrate such as a glass substrate in the periphery of the foreign substance (dust), and a semiconductor layer deficiency region is generated. The semiconductor layer deficiency region which is generated at the time is larger than the size of the foreign substance (dust). In the case where a diameter of the foreign substance (dust) is 1 μm, the semiconductor layer deficiency region grows approximately 1000 μm in diameter. Of course, a device formed in the semiconductor layer deficiency region becomes a defect.
There has already been a technique for repairing a deficiency portion generated in an SOI substrate manufactured by an attaching method (Reference 2: Japanese Published Patent Application No. H8-250421). In this repairing technique, an amorphous silicon film is formed over the entire surface of a single crystal silicon layer, and after crystallizing the entire surface by heat treatment or laser processing, the amorphous silicon film is planarized by polishing treatment, thereby repairing the deficiency portion.